Nicotine and Tobacco Specific Nitrosamine exposure among youth in England who smoke cigarettes and/or vape

Significance: Compared with adults who smoke cigarettes, adults who vape nicotine are exposed to similar levels of nicotine and significantly lower levels of tobacco-specific nitrosamines (TSNAs). Little research outside the US has included youth who vape, particularly those using newer disposable vapes. We investigated exposure to nicotine and the TSNA NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol) among youth in England who vape, smoke, do both (dual), or do neither.Methods: In 2023, youth aged 16-19 from England completed a survey and provided a urine sample (N=201). Linear regressions examined associations of creatinine-normalised urinary concentrations of Total Nicotine Equivalents (TNE-2) and NNAL (a metabolite of NNK) with past 7-day smoking/vaping status and self-reported recency of vaping. All analyses were adjusted for age, sex-at-birth, ethnicity, and any past 7-day cannabis use. Findings:Over three quarters (77%) of those vaping were using the newer disposable vapes. Urinary TNE-2 concentrations among those who exclusively vaped in the past 7 days (n=83, geometric mean (GM)=5.09 nmol/mg creatinine [95%CI=3.19-8.12]) did not differ significantly from those who smoked (n=9,GM=1.74[0.64-4.72],p=.426) or dual used (n=55, GM=5.60[3.32-9.43],p=.953). Levels of NNAL among those who exclusively vaped (GM=1.87 pg/mg creatinine[1.62-2.17]) were significantly lower than those who smoked (GM=4.87,p=.001[2.45-9.68]) or dual used (GM=3.67[2.76-4.86],p<.001) and not significantly different from youth who neither vaped nor smoked (GM=1.84[1.52-2.24],p=.887).Interpretation:Youth who vape are exposed to similar levels of nicotine compared to those who smoke or who dual use. NNAL exposure among youth who vape is much lower than those who smoke, and indistinguishable from youth who do not vape or smoke.